Factors that can influence results


Centrifugation which is overly exposed to air can lead to secondary coagulation causing the serum to have a gelatinous consistency.

By letting the serum rest in a plastic or glass recipient and centrifuging it again, it will return to its normal fluidity. The rare cases where the consistency does not change are proof of the presence of pathological proteins, and we must then consider plasmacytoma or multiple myeloma.


Hyperbilirubinemia is the consequence of an increase in the amount of bilirubin in the gallbladder, which leads to a yellowish colouring of the blood sample.

Its causes are linked to liver damage, and in acute cases they can be linked to haemolytic anaemia. Physiological bilirubinaemia in horses is from 3.1 mg /dL. It is not influenced by the technique of the sample.


Lipaemia, because of the accumulation of microscopic droplets of fat, can make the serum appear milky.

Causes of lipaemia can be linked to abnormalities in fats’ metabolism, diabetes, acute pancreatitis, Cushing’s syndrome, or to a diet that is too rich in fats. To identify post-prandial physiological lipaemia from an illness, if possible, a diet must be followed for 8 to 12 hours before the blood test.


The bursting of erythrocytes leads to a reddish colour in the serum or plasma. Erythrocytes can be broken due to:

  • Haemolysis (haemolytic anaemia)
  • An incorrect sampling technique, such as strong aspiration, blood being shaken or ejected (forming a mousse),
  • Incorrect handling after the sample is taken, for example, if the blood is left for too long or is kept too cold or too warm, with an overly intense centrifugation, or if the blood is shaken a lot during transport.

Haemolysis leads to false results, particularly concerning measurements of potassium, magnesium, iron, phosphates, CK enzymes, LDH, AST and ALT, hormones and serological parameters. This can be avoided by using a correct sampling technique and by implementing centrifugation within a suitable time.

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